In Australia, most families have annual holidays between late December to January. Williamstown is a very popular destination for holiday makers over this holiday period, so I suggest you book early!
Below are some accommodation venues in the area:
There are also a number of rooms, apartments, town-houses and homes available privately through portals such as Hometogo and airBnB
Surrounding suburbs to Williamstown are Newport, Yarraville, Altona North, Altona, Brooklyn, Footscray and Laverton. Melbourne's CBD is about a 15 minute train ride.